1. Field of the Invention
The present invention relates to a PC card apparatus controlling the switching of a plurality of card information structures (hereinafter called CISs) provided for a PC card and also controlling the switching of power sources for a plurality of functions provided for the PC card in synchronization with the switching of the CISs.
2. Description of the Related Art
A PC card is inserted into a slot of a personal computer and used. It is provided with a CIS, which indicates the attribute information of the PC card, and functions such as a modem, a local area network (LAN), and memory.
In a conventional general PC card, one function and one CIS indicating the attribute information of the function are provided, as shown in FIG. 3A. It is of a so-called single type. When such a single-type PC card 1 is used, if a plurality of functions are to be used in a time-series manner, a plurality of PC cards having different functions need to be inserted into a personal computer alternately, which is troublesome.
To eliminate this troublesome work of changing PC cards, a so-called multiple-type PC card has been recently used which provides two functions, such as a modem and a LAN function or a modem and memory, and one CIS indicating the attribute information of the two functions, as shown in FIG. 3B. To use such a multiple-type PC card, a driver (driving mechanism) having multifunction capability needs to be provided for a personal computer. When a multiple-type PC card is inserted into a personal computer having this driver having multifunction capability, the attribute information of two functions, function 1 and function 2, is read through one CIS to the personal computer and the two functions become available.
CIS data indicating the attribute information of the PC card 1 is provided for the card according to a rule which conforms to the PC card standard, which is standardized by PCMCIA of the United States and JEIDA of Japan. A personal computer reads data from the PC card 1 according to the card standard.
When a personal computer is not provided with a driver having multifunction capability, since the personal computer can read data only from a single-type PC card, even if a multiple-type PC card is inserted in the personal computer, the card cannot be used.
When a multiple-type PC card is inserted into a personal computer provided with a driver having multifunction capability, two functions provided for the card can be used. If only one of the two functions is to be used, for example, since the personal computer reads CIS data for the two functions and makes the environment ready for the two functions, the function not to be used is also made available with the corresponding circuit being driven, and power is wasted.
When the PC card 1 is provided with two functions, a modem and an ATA memory, the modem needs a current of about 120 mA and the ATA memory requires a current of about 1 mA (when idling). If only the function of ATA memory is used, although just a current of 1 mA is required, since the function of the modem is also made ready with the corresponding circuit being driven, a current of 121 mA is consumed. In the PC card 1 provided with the functions of a modem and an ATA memory, usually the ATA memory is relatively frequently used, and the function of the modem is generally used only for communication less frequently. Every time when the ATA memory is used, a high current flows into the modem and the current is wasted. Therefore an improvement is demanded.